/**
 * 仿射变换：warpAffine()
 * 1. Rotations (linear transformation)：getRotationMatrix2D()
 * 2. Translations (vector addition)：getAffineTransform()
 * 3. Scale operations (linear transformation)：getRotationMatrix2D()
 */

#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main(int argc, char *argv[]) {
    //! [Load the image]
    CommandLineParser parser(argc, argv, "{@input | lena.jpg | input image}");
    Mat src = imread(samples::findFile(parser.get<String>("@input")));
    if (src.empty()) {
        cout << "Could not open or find the image!\n" << endl;
        cout << "Usage: " << argv[0] << " <Input image>" << endl;
        return -1;
    }
    //! [Load the image]

    //! [Set your 3 points to calculate the  Affine Transform]
    Point2f srcTri[3];
    srcTri[0] = Point2f(0.f, 0.f);
    srcTri[1] = Point2f(src.cols - 1.f, 0.f);
    srcTri[2] = Point2f(0.f, src.rows - 1.f);

    Point2f dstTri[3];
    dstTri[0] = Point2f(0.f, src.rows * 0.33f);
    dstTri[1] = Point2f(src.cols * 0.85f, src.rows * 0.25f);
    dstTri[2] = Point2f(src.cols * 0.15f, src.rows * 0.7f);
    //! [Set your 3 points to calculate the  Affine Transform]

    //! [Get the Affine Transform]
    Mat warp_mat = getAffineTransform(srcTri, dstTri);
    //! [Get the Affine Transform]

    //! [Apply the Affine Transform just found to the src image]
    /// Set the dst image the same type and size as src
    Mat warp_dst = Mat::zeros(src.rows, src.cols, src.type());

    warpAffine(src, warp_dst, warp_mat, warp_dst.size());
    //! [Apply the Affine Transform just found to the src image]

    /** Rotating the image after Warp */

    //! [Compute a rotation matrix with respect to the center of the image]
    Point center = Point(warp_dst.cols / 2, warp_dst.rows / 2);
    double angle = -50.0;
    double scale = 0.6;
    //! [Compute a rotation matrix with respect to the center of the image]

    //! [Get the rotation matrix with the specifications above]
    Mat rot_mat = getRotationMatrix2D(center, angle, scale);
    //! [Get the rotation matrix with the specifications above]

    //! [Rotate the warped image]
    Mat warp_rotate_dst;
    warpAffine(warp_dst, warp_rotate_dst, rot_mat, warp_dst.size());
    //! [Rotate the warped image]

    //! [Show what you got]
    imshow("Source image", src);
    imshow("Warp", warp_dst);
    imshow("Warp + Rotate", warp_rotate_dst);
    //! [Show what you got]

    //! [Wait until user exits the program]
    waitKey();
    //! [Wait until user exits the program]

    return 0;
}
